Topographic Maps for iPhone

Thu, 03/19/2009 - 8:51am

brentrn

7 years

An application for GPS enabled iPhone's (currently the 3G model) offers US Geologic Survey (USGS) survey maps superimposed with your location. The application is $10 and covers the USA. It looks like you cannot zoom in on the maps or use it for wilderness travel. Because the maps are residing in the phone you do not need a network connection. This may a useful adjunct when traveling far off the major highway or to see what kind of terrain is ahead.

This doesn't appear to be a true replacement for a trail GPS but for $10 it takes advantage of the iPhone's memory, processor, and GPS antenna. I would suggest taking along external batteries if you decide to use this.

TopoPointUSA

Hi,
I'd like to clarify that TopoPointUSA was developed specifically for wilderness travel.

We don't recommend it for roadway use because USGS maps were not developed for that purpose.

As of now, zooming is not supported. However, our usage/field testing indicates zooming is not really necessary when viewing this type of map data. We believe the Google maps iPhone app is cool, but it seems to have set an expectation that is not really applicable to TopoPoint's purpose. Google maps gets small tiles from a web server and only caches an area slightly larger than the screen at a single zoom level. As a user zooms in Google Maps, new tiles are requested from their server - it will "resample and display" the current tiles while requesting new tiles, but as you probably have observed such tiles are not very useable and only really serve as a placeholder until the new tiles arrive over the internet.

Since offline storage is a central purpose of TopoPoint, and resampling map data does not yield acceptable results, we chose to fix the resolution to the highest practical level. And we used the iPhone's processing power to present more robust map scrolling than Google maps, which we believe is a more economical use of the iPhone's limited capabilities.

Our field testing has determined that TopoPointUSA is accurate enough to determine whether you are standing in your front or back yard (provided your house is on the USGS map), or what side of a street/river/trail/.. you are on. If you are standing at a specific feature on the USGS map (e.g. trail intersection, switchback, well, spring, etc) TopoPointUSA pegs you right on that map feature (provided the GPS accuracy is available, which is shown in TopoPoint's position indicator).

We strived to offer a valuable v1.0 feature set to support TopoPoint's main purpose and live within the iPhone's current hardware limitations. While it was tempting to spend development efforts on nonessential features such as zooming, we believe such features would come at the high cost of battery charge.